Etymologically the term blasphemy comes from the Greek "blaptein" which means "to injure" and "pheme" which means "reputation" . Therefore blasphemy is considered as an offense or sacrilege towards God or some sacred object. Likewise, this term also refers to any affront or injury that is made to any respectable individual or element.
So blasphemy is every word that is pronounced against a person in an insulting way, although in this case it would be called insult or defamation, rather blasphemy is linked to everything sacred, with everything that has to do with God and the church. The religion considers that infamy or outrage towards God should be appreciated as a mortal sin and only if they are said without intention or due to lack of knowledge is when they can be considered venial sins, the church could grant forgiveness to those who commit blasphemy, as long as the blasphemy was not against the holy spirit, since the church considers this offense as an extremely serious sin.
There are some countries that have a legal framework against blasphemy, and where committing this type of acts can be punished by law. Many religions sanction those who dare to blaspheme a temple or any religious image, even many of them apply the most cruel punishments for those who dare to blaspheme, however one of the most drastic sanctions or punishments that could have been applied, is undoubtedly the death penalty, unfortunately many countries of Arab origin still contemplate the application of this type of sanctions.
Anyone who commits blasphemy is considered a blasphemer, and can be identified by the way he speaks or thinks about things considered by religion as sacred, these kinds of people are frowned upon and are worthy of contempt by people who are they are offended by them.